A photoemission study of liquid and solid thallium, lead and bismuth

Abstract

Ultra-violet photoemission (hω⩽ 21.2 eV) measurements for Tl, Pb and Bi in the liquid and solid (frozen) states are reported. The spectra for the solid phase are consistent with other published data and are broadly similar to the spectra for the liquid phase. Some loss of detail in the spectra for Tl and Bi is attributed to changes of ionic structure on melting. Optical-density-of-states functions for the liquid phase are derived using the three-step model. Significant deviation from the prediction of weak scattering formalisms are found, features associated with the 6s and 6p levels are clearly distinguished. The calculated imaginary part of the dielectric constant, taking account of both Drude and interband transitions, is consistent with experiment.